This invention relates to a fluid material filling apparatus and a fluid material filling method which is capably of stuffing a fluid material not only into a through hole or a shallow closed-end bore but also into a specific closed-end bore having a very small size in diameter and/or depth.
Conventionally, a printed circuit board is provided with via holes formed in an insulating substrate body thereof. A screen printing method is generally used to fill the via holes with a conductive paste serving as a fluid material.
According to a conventional screen printing method for filling the via holes with a conductive paste, a first step is preparing a screen plate with penetration apertures located at predetermined portions corresponding to via holes to be formed. In the next step, the screen plate is placed on the insulating substrate body. Then, the conductive paste is supplied onto the screen plate. Then, the conductive paste on the screen plate is moved or wiped from one end to the other end along a screen surface under the condition that the screen plate is pushed by a squeegee. Thus, under the pressure given by the squeegee, the conductive paste penetrates the penetration apertures and enters into the via holes.
According to the above-described conventional method, it is possible to forcibly push the paste material into a through hole. However, this conventional method is not preferably applicable to via holes with bottoms. For example, when a wiring pattern pad is placed at the bottom of a substrate, via holes opened across the substrate body necessarily have bottoms. In such a case, the residual air in the bottom of each via hole cannot be smoothly replaced by the paste material. Accordingly, undesirable voids of residual air will remain in the bottom of respective via holes. This problem will be severe when the mounting density of electronic elements on a printed circuit board is increased and when the diameter of respective via holes becomes small or when the depth of respective via holes becomes deep.
In view of the above-described problems, the present invention has an object to provide a fluid material filling apparatus and a fluid material filling method which are capable of sufficiently filling a closed-end hole with a fluid material, and especially capable of supplying the fluid material deeply into the bottom of respective holes formed in a substrate.
In order to accomplish the above and other related objects, the present invention provides a first filling apparatus for filling a hole of a substrate with a fluid material, comprising a scavenging section for forming a first hermetically closed chamber when brought into contact with a substrate surface and for depressurizing the first hermetically closed chamber, a fluid material filling section for forming a second hermetically closed chamber when brought into contact with the substrate surface and for stuffing the fluid material into the hole of the substrate within the second hermetically closed chamber, and shifting means for shifting the second hermetically closed chamber of the fluid material filling section to a position of the hole of the substrate after the hole of the substrate is depressurized in the first hermetically closed chamber of the scavenging section. The second hermetically closed chamber is provided adjacent to the first hermetically closed chamber. The fluid material filling section comprises a supply section for supplying the fluid material onto a substrate surface within the second hermetically closed chamber and a squeezing unit for pushing the fluid material into the hole of the substrate within the second hermetically closed chamber.
According to the above-described first fluid material filling apparatus, the scavenging section depressurizes the first hermetically closed chamber so that the air or gas in the hole positioned in the first hermetically closed chamber is scavenged. Then, the second hermetically closed chamber of the fluid material filling section shifts on the substrate surface so as to arrive on the hole thus depressurized. In this condition, the fluid material filling section pushes the fluid material into the depressurized hole. In this case, as the air or gas in the hole is sufficiently scavenged beforehand, the fluid material surely enters into the hole. The inside space of the hole can be entirely filled with the fluid material.
According to the first fluid material filling apparatus, it is preferable that the squeezing unit causes a motion selected from the group consisting of a rotational motion, an orbital motion, and a swing motion in the second hermetically closed chamber. The rotating or swinging squeezing unit is effective to push the fluid material from different directions. Thus, it becomes possible to surely fill the hole with the fluid material.
According to the first fluid material filling apparatus, it is preferable that the squeezing unit includes a sliding member which slides on the substrate surface. The sliding member can wipe the fluid member supplied on the substrate surface and convey the collected fluid material into the hole.
According to the first fluid material filling apparatus, it is preferable that the sliding member is constituted by a rectangular elastic body inclined with respect to the substrate surface. Positioning the sliding member in an inclined relationship with the substrate surface makes it possible to produce a force for pushing the fluid material into the hole at the given angle. The hole can be sufficiently filled with the fluid material. When the sliding member is made by an elastic body having spilt rectangular portions, each rectangular elastic piece can flexibly respond to the rotation or shifting directional change of the squeezing unit and also can follow the undulation of the substrate surface. The contact between the sliding member and the substrate surface can be appropriately maintained. Accordingly, the sliding member can effectively capture the fluid material supplied on the substrate surface at higher probabilities. Thus, the hole can be surely filled with the fluid material.
According to the first fluid material filling apparatus, it is preferable that the supply section holds the fluid material at a predetermined upper position above the squeezing unit within the second hermetically closed chamber, and supplies the fluid material onto the substrate surface via a clearance between a side wall of the second hermetically closed chamber and the squeezing unit. This arrangement requires no special mechanism for supplying the fluid material because the fluid material surely flows down onto the substrate surface from the upper position above the squeezing unit. Furthermore, when the squeezing unit causes a rotational motion, the rotational movement of the squeezing unit can promote the flow of the fluid material directed toward the substrate surface. In this respect, rotating the squeezing unit is preferable. Especially, when the squeezing unit causes an orbital motion in the second hermetically closed chamber, the clearance between the squeezing unit and the second hermetically closed chamber increases or decreases cyclically. This cyclic change of the clearance between the squeezing unit and the second hermetically closed chamber can produce a pump function for surely moving or pushing the fluid material.
According to the first fluid material filling apparatus, it is preferable that the fluid material filling apparatus further includes a depressurizing device for depressurizing the second hermetically closed chamber. If a significant amount of air or gas remains in the second hermetically closed chamber, the residual air or gas and the fluid material will flow into the hole depressurized in the first hermetically closed chamber at the moment the depressurized hole relocates into the second hermetically closed chamber. This will result in an undesirable filling operation of the fluid material.
According to the first fluid material filling apparatus, it is preferable that the second hermetically closed chamber is depressurized to a lower vacuum level compared with the first hermetically closed chamber. In general, when the second hermetically closed chamber accommodating the fluid material is depressurized to a higher vacuum level, a problem such that a solvent contained in the fluid material promptly evaporates will arise. The fluidity of the fluid material will be worsened. This will waste the fluid material at an earlier timing and necessitate an operator or a worker to get a new fluid material. As a result, consumption of the fluid material will increase. On the other hand, when the second hermetically closed chamber is kept at a moderate vacuum level, it becomes possible to prevent the fluid material from deteriorating and also prevent the air or gas from entering in the hole.
According to the first fluid material filling apparatus, when the substrate has a plurality of holes, it is preferable that the first hermetically closed chamber of the scavenging section and the second hermetically closed chamber of the fluid material filling section cause a shifting motion with respect to the substrate so as to stretch over an entire region including all of the plurality of holes. This makes it possible to easily stuff the fluid material into the plurality of holes of the substrate.
According to the first fluid material filling apparatus, it is preferable that control means is provided for controlling a depressurized condition of the scavenging section and also controlling a shifting condition of the shifting means. The first hermetically closed chamber has an annular shape surrounding the second hermetically closed chamber. The control means shifts the first and second hermetically closed chambers to perform an initial fluid material filling operation for stuffing the fluid material into a hole of the substrate under a condition that the first hermetically closed chamber is depressurized. And then, the control means relieves the depressurized condition of the first hermetically closed chamber and shifts the first and second hermetically closed chambers so as to again move on the hole having been once filled with the fluid material to perform a fluid material refilling operation for stuffing additional fluid material into the hole having been once filled with the fluid material.
When the first hermetically closed chamber of the scavenging section surrounds the second hermetically closed chamber, the first hermetically closed chamber located at the leading side of the second hermetically closed chamber has a function of scavenging the air or gas from the hole. However, the first hermetically closed chamber located at the trailing side of the second hermetically closed chamber has a function of sucking the fluid material out of the hole. The fluid material may peel off a hole surface. To avoid this, a fluid material refilling operation is performed under the condition that the first hermetically closed chamber is kept at a moderate level substantially equivalent to the atmospheric pressure. Thus, it becomes possible to fill the paste until it surely reaches the hole surface.
According to the first fluid material filling apparatus, it is preferable that the control means causes the first and second hermetically closed chambers to shift at a first speed during an initial fluid material filling operation, and then causes the first and second hermetically closed chambers to shift at a second speed higher than the first speed during a fluid material refilling operation.
To form the first and second hermetically closed chambers on the substrate surface, each of the scavenging section and the fluid material filling section has a contact portion brought into contact with the substrate surface. During the fluid material filling operation for filling the hole having a bottom formed in the substrate, the fluid material adheres to the contact portion. During the shifting operation of the first and second hermetically closed chambers, the fluid material adhered to the contact portion is brought into contact or merges with the fluid material in the hole. In this case, the fluid material in the hole is drawn by the fluid material adhered to the contact portion and there is the possibility that the fluid material in the hole may be pulled out of the hole. To solve this problem, increasing the shifting speed of the first and second hermetically closed chambers during the fluid material refilling operation is effective to promptly separate the fluid material in the hole from the fluid material adhered to the contact portion. This surely prevents the fluid material from being pulled out of the hole, and stabilizes the amount of the fluid material in the hole.
During the initial fluid materia filling operation, it is necessary to sufficiently supply the fluid material deeply into the bottom of the hole. To this end, it is desirable to set the shifting speed of the first and second hermetically closed chambers at a relatively slow speed. On the other hand, during the fluid material refilling operation, the hole is almost filled with the fluid material and therefore stabilizing or adjusting the filling amount of the fluid material is important. To this end, it is preferable to supply a small amount of fluid material into the hole by increasing the shifting speed of the first and second hermetically closed chambers.
Furthermore, according to the first fluid material filling apparatus, it is preferable that the fluid material filling apparatus comprises control means for controlling a depressurized condition of the scavenging section and also controlling a shifting condition of the shifting means. The first hermetically closed chamber and the second hermetically closed chamber are aligned next to each other. The control means controls the shifting means so that the first hermetically closed chamber of the scavenging section and the second hermetically closed chamber of the fluid material filling section shift in both forward and backward directions on the substrate. In a forward stroke of the first and second hermetically closed chambers, the control means highly depressurizes the first hermetically closed chamber located at a leading side of the second hermetically closed chamber and sets a shifting speed of the first and second hermetically closed chambers at a first speed. And then, in a backward stroke of the first and second hermetically closed chambers, the control means relieves the depressurized condition of the first hermetically closed chamber located at a leading side or a trailing side of the second hermetically closed chamber and changes the shifting speed of the first and second hermetically closed chambers to a second speed higher than the first speed.
In this manner, it is preferable to arrange the first hermetically closed chamber and the second hermetically closed chamber so as to be positioned next to each other. Maintaining the first hermetically closed chamber of the scavenging section at a highly depressurized condition and shifting the first and second hermetically closed chambers at a lower speed (i.e., first speed) in the forward stroke is effective to sufficiently fill the fluid material into the hole. Furthermore, relieving the depressurized condition of the first hermetically closed chamber and shifting the first and second hermetically closed chambers at a higher speed (i.e., second speed) in the backward stroke is effective to prevent the fluid material in the hole from being pulled out of the hole and also effective to stabilize or adjust the amount of the fluid material in the hole.
The present invention provides a second filling apparatus for filling a plurality of holes of a substrate with a fluid material, comprising a first scavenging section for forming a first hermetically closed chamber when brought into contact with a substrate surface and for depressurizing the first hermetically closed chamber, and a second scavenging section for forming a second hermetically closed chamber when brought into contact with the substrate surface and for depressurizing the second hermetically closed chamber. A fluid material filling section is provided for forming a third hermetically closed chamber between the first and second hermetically closed chambers when brought into contact with the substrate surface and for stuffing the fluid material into the holes of the substrate within the third hermetically closed chamber. A shifting means is provided for shifting the first hermetically closed chamber of the first scavenging section, the second hermetically closed chamber of the second scavenging section, and the third hermetically closed chamber of the fluid material filling section. And, a control means is provided for controlling a depressurized condition of the first and second scavenging sections and also controlling a shifting condition of the shifting means. The fluid material filling section comprises a supply section for supplying the fluid material onto a substrate surface within the third hermetically closed chamber and a squeezing unit for pushing the fluid material into the holes of the substrate within the third hermetically closed chamber. The control means controls a shifting direction of the shifting means so that the first to third hermetically closed chambers shift in both forward and backward directions on the substrate. In a forward stroke of the first to third hermetically closed chambers, the control means depressurizes the first hermetically closed chamber located at a leading side of the third hermetically closed chamber to a first depressurized condition and sets a shifting speed of the first to third hermetically closed chambers at a first speed. And, in a backward stroke of the first to third hermetically closed chambers, the control means depressurizes the second hermetically closed chamber located at a leading side of the third hermetically closed chamber to a second depressurized condition which is relieved than the first depressurized condition and changes the shifting speed of the first to third hermetically closed chambers to a second speed higher than the first speed being set in the forward stroke.
Arranging the first and second hermetically closed chambers at front and rear sides of the third hermetically closed chamber of the fluid material filling section makes it possible to provide an appropriate depressurized space at the leading side of the third hermetically closed chamber of the fluid material filling section in each of the forward and backward strokes, without requiring the shifting assembly consisting of the first to third hermetically closed chambers to change the alining direction.
Then, in the forward stroke, to supply the fluid material deeply into the bottom of each hole, the first hermetically closed chamber is maintained at a highly depressurized condition (i.e., first depressurized condition) and the shifting speed is set to a lower speed (i.e., first speed). This makes it possible to assure a sufficient amount of filling amount.
On the other hand, in the backward stroke, the second hermetically closed chamber is maintained at a moderately depressurized condition (i.e., second depressurized condition) and the shifting speed is set to a higher speed (i.e., second speed). This makes it possible to prevent the fluid material in each hole from being pulled out of the hole when the hole relocates in the second hermetically closed chamber. Then, under the condition that the shifting speed is increased, a small amount of the fluid material is supplied to refill each hole. This effectively prevents the fluid material in each hole from being drawn by the fluid material adhered to the contact portion between each hermetically closed chamber and the substrate surface. Thus, the amount of the fluid material in each hole can be stabilized.
According to the second fluid material filling apparatus, it is preferable that in the forward stroke, the control means depressurizes the second hermetically closed chamber of the second scavenging section located at a trailing side of the third hermetically closed chamber of the fluid material filling section to a third depressurized condition which is relieved than the first depressurized condition. This makes it possible to prevent the fluid material in each hole from being sucked out of the hole by the second scavenging section at the moment each hole relocates in the second hermetically closed chamber. Preferably, the third depressurized condition is substantially equivalent to the atmospheric pressure.
According to the second fluid material filling apparatus, it is preferable that in the backward stroke, the control means depressurizes the first hermetically closed chamber of the first scavenging section located at a trailing side of the third hermetically closed chamber of the fluid material filling section to a fourth depressurized condition which is relieved than the second depressurized condition. This makes it possible to prevent the fluid material in each hole from being sucked out of the hole by the first scavenging section at the moment each hole relocates in the first hermetically closed chamber. Preferably, the fourth depressurized condition is substantially equivalent to the atmospheric pressure.
To accomplish the above and other related objects, the present invention further provides a first filling method for filling a hole of a substrate with a fluid material, comprising a step of forming a first hermetically closed chamber partly defined by a predetermined region of a substrate surface and depressurizing the first hermetically closed chamber, a step of forming a second hermetically closed chamber defined by a predetermined region of the substrate surface and positioned adjacent to the first hermetically closed chamber, a step of supplying the fluid material onto a substrate surface within the second hermetically closed chamber, and a step of shifting the first and second hermetically closed chambers in a direction from the second hermetically closed chamber to the first hermetically closed chamber and pushing the fluid material supplied on the substrate surface by using a squeezing member into a hole of the substrate depressurized in the first hermetically closed chamber when the depressurized hole relocates into the second hermetically closed chamber.
According to the first fluid material filling method, it is preferable that the squeezing member causes a motion selected from the group consisting of a rotational motion, an orbital motion, and a swing motion in the second hermetically closed chamber. The fluid material is held at a predetermined upper position above the squeezing member within the second hermetically closed chamber, and is supplied onto the substrate surface via a clearance between a side wall of the second hermetically closed chamber and the squeezing member. Furthermore, it is preferable that the first fluid material filling method comprises a step of depressurizing the second hermetically closed chamber. The second hermetically closed chamber is depressurized to a lower vacuum level compared with the first hermetically closed chamber.
When the substrate has a plurality of holes, it is preferable that the first and second hermetically closed chambers cause a shifting motion with respect to the substrate so as to stretch over an entire region including all of the plurality of holes, so that the plurality of holes of the substrate are filled with the fluid material.
For example, the first hermetically closed chamber has an annular shape surrounding the second hermetically closed chamber. An initial fluid material filling operation is performed by shifting the first and second hermetically closed chambers to stuff the fluid material into a hole of the substrate depressurized in the first hermetically closed chamber when the depressurized hole relocates into the second hermetically closed chamber. And, a fluid material refilling operation is performed by relieving a depressurized condition of the first hermetically closed chamber to a level substantially equal to the atmospheric pressure and shifting the first and second hermetically closed chambers to stuff additional fluid material into the hole having been once filled with the fluid material under such a relieved pressure condition.
In this case, the first and second hermetically closed chambers are shifted at a first speed during the initial fluid material filling operation, and then the first and second hermetically closed chambers are shifted at a second speed higher than the first speed during the fluid material refilling operation.
Alternatively, the first hermetically closed chamber and the second hermetically closed chamber can be aligned next to each other, and are shifted in both forward and backward directions on the substrate during the step of pushing the fluid material into the depressurized hole of the substrate. In a forward stroke of the first and second hermetically closed chambers, the first hermetically closed chamber located at a leading side of the second hermetically closed chamber is highly depressurized and a shifting speed of the first and second hermetically closed chambers is set to a first speed. And, in a backward stroke of the first and second hermetically closed chambers, the depressurized condition of the first hermetically closed chamber located at a leading side or a trailing side of the second hermetically closed chamber is relieved and the shifting speed of the first and second hermetically closed chambers is set to a second speed higher than the first speed.
Moreover, the present invention provides a second filling method for filling a plurality of holes of a substrate with a fluid material, comprising a step of forming a first hermetically closed chamber partly defined by a predetermined region of a substrate, forming a second hermetically closed chamber partly defined by a predetermined region of the substrate, and a third hermetically closed chamber between the first and second hermetically closed chambers partly defined by a predetermined region of the substrate, a step of supplying the fluid material onto a substrate surface within the third hermetically closed chamber, a step of performing an initial fluid material filling operation for depressurizing the first hermetically closed chamber to a first depressurized condition and shifting the first to third hermetically closed chambers at a first speed in a direction from the third hermetically closed chamber to the first hermetically closed chamber so as to stuff the fluid material on the substrate surface into holes of the substrate depressurized in the first hermetically closed chamber when the depressurized holes relocate into the third hermetically closed chamber, and a step of performing a fluid material refilling operation for depressurizing the second hermetically closed chamber to a second depressurized condition relieved than the first depressurized condition and shifting the first to third hermetically closed chambers in a direction from the third hermetically closed chamber to the second hermetically closed chamber at a second speed higher than the first speed so as to stuff the fluid material on the substrate surface into the holes of the substrate depressurized in the second hermetically closed chamber when the depressurized holes relocate into the third hermetically closed chamber.
According to the second fluid material filling method, it is preferable that, during the initial fluid material filling operation, the second hermetically closed chamber located at a trailing side of the third hermetically closed chamber is depressurized into a third depressurized condition which is relieved than the first depressurized condition.
According to the second fluid material filling method, it is preferable that, during the fluid material refilling operation, the first hermetically closed chamber located at a trailing side of the third hermetically closed chamber is depressurized into a fourth depressurized condition which is relieved than the second depressurized condition.
Their functions and effects of the fluid material filling method are similar to those of the above-described filling apparatus.